The invention relates to the monitoring and replacement of field replaceable units (FRUs) for electronic equipment, for example for a telecommunications or other application where high standards are set and where the unit may, for example, be remote from a service center and the replacement may need to be effected by non-skilled personnel.
FRUs can be used in many different systems. They find particular but not exclusive application to computer systems, for example to fault tolerant computer systems where it is desirable to be able readily to replace units which have developed a fault or have been superseded by a more recent version.
Examples of FRUs for such a system can include, for example, a CPU, a PCI card, power supply units (PSUs), a motherboard, or any other system components. One FRU, for example a field replaceable card, can include hardware for implementing several devices (e.g. a multiple Ethernet adapter, or a SCSI adapter with an Ethernet adapter).
It is known to provide FRUs with non-volatile memory (e.g. EEPROMs), which can contain information relating to the FRU. In a known system, FRUs can include basic FRU identification information in the non-volatile memory.
It is also known to provide a system management suite, collectively known as a configuration management system (CMS) which manages the FRUs, other devices and system resources using objects to represent the FRUs, devices and other system resources. An object forms a particular instance of a CMS class, which is defined by a CMS definition (CMSDEF).
For example, a CAF (Console and Fans unit) CMSDEF defines the CAF CMS class of which the object CAF.sub.-- 1 is an instance that represents a particular CAF FRU. The CAF 1 object may have an attribute called LOCATION having the value A_CAF in the chassis of the computer system.
In order correctly to manage the FRUs, the CMS requires access to the non-volatile memory in the FRUs. In order to gain access to the non-volatile memory in the FRUs, it is necessary that power is supplied to the FRUs. However, this conflicts with safety requirements relating to telecommunications equipment which require that when a unit is faulty, for example a FRU, it is necessary to power down that unit. For example, an electrical fault can cause a fuse blow, isolating the FRU electrically. In such a situation, access to the memory storing the data about the FRU can be lost, making identification and/or diagnosis of the fault more difficult, or impossible.
Accordingly, present invention seeks to improve fault identification and/or diagnosis for a FRU provided with a power isolation mechanism.